A one-piece conveyor flange adapter designed for hollow bore, direct drive configurations. A dual flange casting has two opposite flanges machined and bored to attach between a mounting plate on an electric motor speed reducer housing and a similar mounting plate on a conveyor drive frame. The adapter has a large central axial opening between the two parallel plates, through which a rotating drive shaft extends. The adapter is bolted in place between the speed reducer housing and the conveyor drive frame. The flange adapter has a base mounted on the speed reducer. The outer cruciform flange mounts directly on the conveyor frame with two or four bolt connections. The conveyor drive shaft fits through the opening and connects to gears inside the reducer. Alternatively, the reducer has an output shaft that extends through the opening and directly connects to the conveyor drive.